Hierarchical manganese valence gradient MnO2via phosphorus doping for cathode materials with improved stability.

The search for a method for enhancing the electrochemical performance of manganese dioxide is still a challenge. Herein, we report a rod-like P-MnOx cathode material with a hierarchical manganese gradient valence through the phosphatization process. For the incorporation of P, Mn3O4 was formed on the surface of MnO2 and exhibited a gradient valence structure, while the oxygen defect concentration in P-MnOx increased. The unique structure was verified via XRD, TEM and XPS. As the cathode material for a supercapacitor, the specific capacitance of P-MnOx was 126.3 F g-1, which was four times that of MnO2. The assembling of the coin cells of aqueous ZIBs with P-MnOx also showed good rate performance. The electrochemical performance of the synthesised P-MnOx cathode was enhanced for the synergistic effect of improved conductivity and structural stability.

Surface self-reconstructed amorphous/crystalline hybrid iron disulfide for high-efficiency water oxidation electrocatalysis.

Hybrid electrocatalysts derived from surface self-reconstruction during reaction processes can facilitate charge transfer between different phases and nanostructures by their unique interfaces. Herein, amorphous/crystalline hybrid iron disulfide obtained by self-reconstruction is developed for the first time for the oxygen evolution reaction (OER). The amorphous/crystalline hybrid FeS2 catalyst exhibited a high OER activity with an overpotential of only 189.5 mV (IR-corrected) to deliver 10 mA cm-2 in 1.0 M KOH, which was superior to that of the commercial RuO2. Notably, in the two-electrode system with the amorphous/crystalline hybrid FeS2 as the anode electrocatalyst and Pt/C as the cathode, the catalytic activity towards the overall water splitting was enhanced with a voltage of only 1.43 V at 10 mA cm-2. The phase, composition and surface structure were changed greatly before and after the reaction. All these surface reconstructions after the OER reaction may play significant roles in the high electronic catalytic efficiency. Therefore, the study of the surface reconstruction of catalysts during the reaction process is very important for the structure-performance relationship and the design of efficient hybrid electrocatalysts.

Tailor-Engineered POSS-Based Hybrid Gels for Bone Regeneration.

Organic-inorganic oligo(ethylene glycol)-polyhedral oligomeric silsesquioxanes (OEGn-POSS) hybrid materials are woven into macroscopically shaped entities by thiol-ene chemistry. The mechanical behavior and interfacial nature of the OEGn-POSS materials are easily tailored by changing the length of OEGn. The nanostructured OEGn-POSS materials exhibited excellent bioactivity to form hydroxyapatite, whose morphology was also dependent on the molecular weight of OEGn. Among them, OEG2-POSS materials enhanced the in vitro differentiation of adipose-derived stem cells to osteoblasts and promoted the in vivo bone formation within a femoral condyle defect site, but they could be limited by the mismatch rates between the degradation and new bone formation. Thus, OEG2-POSS could be practically applied for bone regeneration by optimizing the degradation rate based on its key structural features, which would be of great benefit to bone tissue engineering in the future.

Preparation and Biomechanical Properties of an Acellular Porcine Corneal Stroma.

PURPOSE: To construct an acellular porcine corneal stroma (aPCS) as a human corneal stroma alternative and to further explore its biomechanical properties. METHODS: A combination of DNA-RNA enzymes and ultrasound technology was used to strip the native porcine corneal cells. The microstructure of aPCS was observed by H&E staining, DAPI staining, and α-Gal tests. The mechanical properties were detected by a tension machine. Cytotoxicity of aPCS was measured by the MTT assay. The subcutaneous embedding experiment in rats was also used to detect immunity and degradation. The aPCS was transplanted into the rabbit cornea by lamellar keratoplasty, general observations were made at 3 days, 1 week, 1 month, and 3 months after implantation, respectively. RESULTS: The microstructure and mechanical properties of aPCS were not damaged during the decellularization process. The aPCS extracts had no significant cytotoxicity on human corneal stroma cells. Moreover, the subcutaneous embedding experiment in rats demonstrated that aPCS could not be degraded and induced no immune reaction in and around the transplanted discs. More important is that the aPCS reconstructed normal corneal stroma and maintained corneal transparency and thickness, with almost no neovascularization and inflammation at 3 months after surgery. CONCLUSIONS: The aPCS prepared in this study had good biocompatibility, safety, and low antigenicity, which has great potential for corneal disease treatment.

Manufacture and property research of heparin grafted electrospinning PCU artificial vascular scaffolds.

PCU (polycarbonate polyurethane) is supposed to be an ideal elastomer for manufacturing artificial vessel scaffold with perfect mechanical strength and biocompatibility. Surface grafting by heparin sodium can increase its anticoagulant hemorrhagic, achieving a better application in artificial vessels. Artificial vessels were preliminarily prepared by electrostatic spinning, treated by NH3 plasma and cross-linked with the anticoagulant heparin sodium chemically. Performances of the PCU-Hep (heparin sodium grafted purethane artificial vessels) artificial vessel were calculated through the physical and chemical property tests, evaluation of blood and biocompatibility. Results manifested that heparin sodium was successfully grafted to the vascular surface, porosity, pore diameter and water permeability of the vascular prosthesis fitted the requirements of artificial vessels, the blood test results demonstrated that the vascular material had a low hemolysis, in vitro cytotoxicity experiment and animal experiments proved an excellent biocompatibility. Thus the heparin sodium grafted electrospinning vessels could reduce intravascular thrombus and had potential clinical application.